Re: [Boost-users] [serialization] Serializing derived template classvia base pointer

17 Jan 2013


      On 2013-01-17 16:35, Daniel Mitchell wrote:
...
Hi Robert, thanks for your reply. Unfortunately I couldn't find any
of the demos to which you refer, but I did find a 2005 boost-users
thread on the subject:
http://thread.gmane.org/gmane.comp.lib.boost.user/13244/
In that discussion you said you did not have a general solution. I'm
just wondering if anything has changed since then e.g maybe C++11
makes a solution possible.
On Jan 17, 2013, at 2:01 PM, "Robert Ramey"  wrote:
...
Daniel Mitchell wrote:
...
Hi everyone, has any progress has been made on a general solution 
for
this problem? Given classes like these,
struct base {
template<typename Archive>
void serialize(Archive& ar, unsigned version) { }
virtual ~base() = default;
};
template<typename T>
struct derived : base {
template<typename Archive>
void serialize(Archive& ar, unsigned version) { ar & data; }
T data;
};
is it possible to serialize the derived type (with T unknown) via a
base pointer? Sticking a call to register_type<derived> in
derived::serialize doesn't seem to do it.
There are several demos in the examples directory which show how to 
do this.
Robert Ramey
I don't totally understand your original issue, but does this possibly 
do what you are wanting ??

#include <fstream>
#include 
#include 
#include 
#include 

struct base {
   template<typename Archive>
   void serialize(Archive& ar, unsigned version) { }

   virtual ~base() { }
};

BOOST_CLASS_EXPORT_KEY(base);
BOOST_CLASS_EXPORT_IMPLEMENT(base);

template<typename T>
struct derived : base {
   derived() { }
   derived(int v) : data(v) { }

   template<typename Archive>
   void serialize(Archive& ar, unsigned version) {
     ar & boost::serialization::base_object<base>(*this);
     ar & data;
   }

   T data;
};

BOOST_CLASS_EXPORT_KEY(derived<int>);
BOOST_CLASS_EXPORT_IMPLEMENT(derived<int>);


int main() {
   base* b = new derived<int>(99);
   std::ofstream o("test.out", std::ios::binary);
   if (o.good()) {
     boost::archive::binary_oarchive oa(o);
     oa & b;
   }
   o.close();
   delete b;


   std::ifstream i("test.out", std::ios::binary);
   if (i.good()) {
     base* b;
     boost::archive::binary_iarchive ia(i);
     ia & b;
     std::cout << static_cast(b)->data << std::endl;
   }
   i.close();
}

Re: [Boost-users] [serialization] Serializing derived template classvia base pointer

Tim Moore